Steel S6-ANN vs S6 QT-56-58
Steel · S6 temper comparison
S6-ANN and S6 QT-56-58 are two conditions of the same steel grade, S6: ANN (annealed) versus QT-56-58 (Q&T 56–58 HRC). The chemistry is identical, so every difference below comes from the condition. S6 QT-56-58 is the stronger of the two: yield strength 1,700 MPa (247 ksi) against 415 MPa (60.2 ksi) for S6-ANN, about 4.1 times as much; tensile strength follows at 2,050 MPa (297 ksi) vs 740 MPa (107 ksi). In exchange, S6-ANN is the more ductile: elongation 22% versus 5% for S6 QT-56-58, and S6 QT-56-58 is harder (640 HV vs 220 HV). S6-ANN runs hotter in service (200°C vs 180°C continuous). On the shop floor, S6-ANN machines more easily (fair vs not recommended).
S6-ANNChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
S6 QT-56-58Choose it when strength drives the design.
S6-ANN vs S6 QT-56-58: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 207 GPa30 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Hardness, Brinell 210 HB · Hardness, Rockwell B 95 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 25 W/m·K14.4 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.4 µm/m·K6.9 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3 % IACS · Electrical Resistivity 5.8×10⁻⁷ Ω·m22.8 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Same in both: Machinability Rating (AISI 1212 = 100 %) 50% · Weldability 20 / 100 · Formability (cold) 35 / 100 · Brazeability / Solderability 30 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 33 MJ/kg14,187 BTU/lb · Embodied Carbon (primary production) 2.4 kg CO₂/kg · Embodied Water 65 L/kg7.8 gal/lb · Typical Recycled Content 40%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
S6-ANN vs S6 QT-56-58 — frequently asked
Is S6 QT-56-58 stronger than S6-ANN?
Yes. S6 QT-56-58 has a typical yield strength of 1,700 MPa (247 ksi) against 415 MPa (60.2 ksi) for S6-ANN — about 4.1 times as much. Tensile strength is 2,050 MPa (297 ksi) vs 740 MPa (107 ksi).
Which condition does FabDigit quote by default, ANN or QT-56-58?
ANN is the default S6 condition in the FabDigit quote flow. The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, S6-ANN or S6 QT-56-58?
S6-ANN. Its machinability rates fair (45/100) against not recommended (5/100) for S6 QT-56-58.
Ready to make it?
Upload a CAD file and FabDigit prices the part in S6-ANN and S6 QT-56-58 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.